Screening methods, genetic variability and correlation studies for Aspergillus flavus resistance in sub-tropical maize (Zea mays L.)

Abstract

Maize is an important cereal crop and a significant contributor to global food and nutritional security. The consumption and nutritional qualities of maize are severely affected by aflatoxin B1. Aflatoxin B1 is a potent carcinogenic,
mutagenic and teratogenic secondary metabolite produced by Aspergillus flavus. Nonchemical and sustainable management of aflatoxin B1 contamination necessitates resistant maize inbred lines for aflatoxigenic
A. flavus and subsequent production of aflatoxin B1. In the present investigation, we have screened thirty diverse Indian maize inbred against aflatoxigenic isolates AF1 and AF3 using kernel screening assay (KSA) method and indirect competitive ELISA (Enzyme-Linked Immunosorbent Assay). The results showed the lower A. flavus colonization (13.33-23.33%) in five maize inbred lines viz., M6, M7, M9, M17 and M22. Similarly, the inbred lines M3, M8, M14, M15 and M17 showed lower aflatoxin B1 concentration (0.09-7.03 μg/g) under both AF1 and AF3 infections. We showed the association and reliability between the rapid lab based KSA screening Side Needle Spore Suspension (SNSS) inoculation methods with five tolerant inbred lines and susceptible lines M2, M4 and M5 and check line M24. The five inbred lines viz., M6, M7, M9, M17 and M22 showed the least infection in field condition (1-2%) compared to M2, M4, M5 and check M24 (92%). Our investigation showed that KSA could be employed for rapid screening of maize genotypes for aflatoxin tolerance and the SNSS inoculation method is more effective in the field. Further, five inbred lines M6, M7, M9, M17 and M22, identified as the resistant source to aflatoxin,
could be employed as candidates for basic and applied maize research in the Indian maize breeding programme.